1. Technical Field
The present invention relates to a carton blank for forming a carton, and a carton which is to be filled with a consumable product accessible through an opening in the carton. More particularly, the invention pertains to an opening feature formed in a top panel of the carton which provides a reliable and a consistent opening when opened by the consumer while reducing the amount of material required in the manufacturing of such carton.
2. Background Art
Paperboard cartons have been manufactured with a variety of opening features which allow the consumer access to the contents of the cartons. These features may consist of perforations, herringbone cuts, adhesive weaknesses, as well as other means of providing a point along the top panel, side panel or hinge lines where the carton may be most readily opened. A further opening feature commonly employed in cartons of this type is that of double-cut scores, as shown in U.S. Pat. No. 3,399,820 to Foster et al. with the top panel including a overlapping panel which overlaps the front side wall of the container.
The above-mentioned opening feature is formed by way of double-cut scores; i.e., an inner and outer cut in the paperboard which run parallel to one another and include cuts extending into the overlapping panel to form a tear flap. By so providing these cut score lines, when the consumer applies an upward force or opening force on the tear flap provided between the pairs of cut score lines, ply separation occurs in the regions between the inner and outer cut score lines. Continued pulling of the tear flap causes complete separation of the opening flap to allow the consumer unobstructed access to the contents of the carton.
Similar opening features are disclosed in U.S. Pat. Nos. 4,746,019 and 4,738,365 to Prater. As with the above-mentioned patent, a line of weakness is provided in a panel of a respective carton where ply separation of the panel is permitted to occur when the consumer applies an opening force to the tear flap. The ply separation occurs between two pairs of reverse cut lines which are formed at least halfway through the panel of the carton. These paperboard blanks are formed in a matrix which consists of a plurality of forming dies and counters. Therefore, by requiring the extended tear flap to be part of an overlapping panel, and consequently requiring an overlapping panel, when forming the blanks in a matrix, a greater amount of paperboard material will be required for each carton blank formed.
U.S. Pat. No. 4,687,104 to Ielmini discloses a similar carton and carton blank having score lines formed in the outer and inner surfaces of the top and the overlapping panel. These score lines are referred to as extending partially through the outer and inner surfaces of the carton and carton blank. Given this assertion, the carton formed by the reverse score lines of U.S. Pat. No. 4,687,104 which includes an overlapping panel requires no less material than with the cartons set forth above. These cartons, as explained above, require an overlapping panel which in turn adds to the amount of paperboard material necessary for the manufacture of such cartons.
In an attempt to overcome the shortcomings associated with the foregoing prior art, U.S. Pat. No. 4,951,824 issued to Kuchenbecker et al., the disclosure of which is hereby incorporated herein by reference, discloses a carton having a reliable opening feature for use in containers wherein it is imperative that the carton remain impervious to moisture or other environmental effects. The opening feature includes an uncut line of weakness extending substantially parallel to a partially cut line of weakness with each of the lines of weakness being formed from the same side of the carton blank. However, this carton also requires the presence of an overlapping panel encompassing a tear flap to permit easy opening of the carton.
U.S. Pat. No. 3,399,820 issued to Foster et al. discloses a carton incorporating a similar opening feature while eliminating the overlapping panel necessary for the positioning of a lift tab. Instead, Foster et al. incorporates the lift tab into the top panel. However, because the lift tab is entirely adhered to the extension panel, the consumer may have difficulty initiating the opening of the carton and once open, the carton is not readily reclosable.
In addition to the aforementioned shortcomings of the various prior art references, each of these cartons must be opened and remain in an open condition when the contents of the carton are heated in a microwave oven in order to permit the egress of steam from within the carton. This may often result in the contents of the carton being dispersed out of the open carton when overheated.
As can be seen from the foregoing, there is clearly a pressing need for a carton of the above-mentioned type which will provide a reliable, and consistent opening feature that is capable of being opened with ease by the consumer, and which will not retard the structural integrity of the carton when opened and, moreover, will result in a reclosable container having a vent opening formed integrally therein while reducing the amount of paperboard material necessary for the manufacture of such carton.